[SERVER-56347] Enable LSE intrinsics in release Created: 26/Apr/21  Updated: 29/Oct/23  Resolved: 24/Jun/21

Status: Closed
Project: Core Server
Component/s: None
Affects Version/s: None
Fix Version/s: 4.2.15, 4.4.7

Type: Task Priority: Major - P3
Reporter: Andrew Morrow (Inactive) Assignee: Andrew Morrow (Inactive)
Resolution: Fixed Votes: 2
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Backports
Depends
Related
related to SERVER-56237 Degraded performance on ARM AWS Gravi... Closed
related to SERVER-51722 Ensure that MongoDB builds with ARM L... Closed
is related to SERVER-56237 Degraded performance on ARM AWS Gravi... Closed
Backwards Compatibility: Fully Compatible
Backport Requested:
v4.4, v4.2
Sprint: Dev Platform 2021-05-31, Dev Platform 2021-06-14, Dev Platform 2021-06-28
Participants:

 Description   

Support for building with -moutline-atomcis was added in SERVER-51722 and backported to v4.4 and v4.2. However, we do not yet have a GCC 8 release which offers that flag. We will need to wait on GCC 8.5 and then upgrade the toolchain. Once that happens, the next releases from v4.4 and v4.2 will use the LSE support. Note that the upcoming v5.0 release will have the LSE intrinsics without needing to wait for a compiler upgrade, because it targets armv8.2-a by default.



 Comments   
Comment by Andrew Morrow (Inactive) [ 24/Jun/21 ]

Closing this: the new toolchain is on the build images. The upcoming 4.4.7 and 4.2.15 releases will be built with -moutline-atomics.

Comment by Andrew Morrow (Inactive) [ 14/Jun/21 ]

The GCC 8.5 toolchain rollout has been completed. I've pulled the latest Amazon Linux 2 builds for v4.2 and v4.4 from CI and validated that they were built with -moutline-atomics and that they contain the LSE instructions per the technique described here: https://github.com/aws/aws-graviton-getting-started/blob/master/c-c%2B%2B.md#large-system-extensions-lse

Support will be available in published builds as of the upcoming v4.2.15-rc0 and v4.4.7-rc0 releases.

Comment by Oliver Yeh [ 18/May/21 ]

Thank you for the update!

Comment by Andrew Morrow (Inactive) [ 18/May/21 ]

Hi oliver@sensortower.com - The internal ticket to upgrade the toolchain to GCC 8.5 is assigned and in progress. There is more than just a bit of process to get a new toolchain into production, but we are actively moving that process forward. We will update this ticket when builds are available with the new codegen.

Comment by Oliver Yeh [ 18/May/21 ]

GCC 8.5 is released!  https://gcc.gnu.org/releases.html  What are the next steps to upgrade the toolchain?

Comment by Andrew Morrow (Inactive) [ 26/Apr/21 ]

This ticket is blocked on our upgrading the v3 toolchain to GCC 8.5, which is expected to be released in a few weeks per https://gcc.gnu.org/pipermail/gcc/2021-April/235871.html

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